Preheat the oven to 375°. Line two large rimmed baking sheets with parchment paper.
In a large bowl, combine the oats, protein powder, almond butter, maple syrup, eggs, mashed banana, yogurt, and all of the spices (ginger through cloves). Mix until well combined.
Add the shredded coconut and cashews. Mix to incorporate. Batter will be wet and heavy.
Scoop the dough into 10 mounds, using about ¼ cup dough for each. Place 5 mounds on each of the prepared baking sheets.
Gently shape and press each cookie into a round disc that is about 2- to 2 ½-inches wide and ½-inch thick.
Bake one sheet at a time on the middle rack for 10 minutes. The cookies may look wet but should be firm to the touch.
Remove from the oven and let the cookies cool on the baking sheet for 5 minutes before transferring to wire racks to cool completely.
If desired, drizzle with icing. In a small bowl or glass measuring cup, whisk together the powdered sugar, milk, and vanilla. Drizzle lightly over the cooled cookies. Garnish with a light dash of nutmeg or cinnamon.
